Molecular Genetics: Gene Isolation, Characterization and Manipulation

Abstract

The information encoded in genetic material (deoxyribonucleic acid, DNA) is responsible for establishing and maintaining the cellular and biochemical functions of an organism. In most organisms, the DNA is an extended double-stranded polymer. The sequence of units (deoxyribonucleotides) of one DNA strand is complementary to the deoxyribonucleotides of the other strand. This complementarity enables new DNA molecules to be synthesized with the same linear array of deoxyribonucleotides in each strand as an original DNA molecule. The process of DNA synthesis is called replication. A specific order of deoxyribonucleotides determines the information content of an individual genetic element (gene). Some genes encode proteins and others RNA molecules. The protein-coding genes (structural genes) are decoded by two successive major cellular processes: RNA synthesis (transcription) and protein synthesis (translation). First, a messenger RNA molecule (mRNA) is synthesized from a structural gene. Second, an individual mRNA molecule interacts with other components including ribosomes, transfer RNAs and enzymes to produce a protein molecule. A protein consists of a precise sequence of amino acids which is essential for its activity.